CVO 1/7/2013A 3/4 charge battery is 12.50 volts
A discharge battery is 11.75 volts.
A battery under a cranking load and it is reading less than 7 volts,it will be a recycled ( junk ) battery.
How to Stop Car Battery Drains: DIY Auto
There are plenty of energy-robbing devices on your car that are supposed to go to sleep when it's parked, and sometimes, not all of them go to sleep. Here's how to give them a tranquilizer